gill cleft vs gill slit

gill cleft and gill slit both are nouns.

Word	Noun	Adjective	Verb	Adverb
gill cleft	Yes	No	No	No
gill slit	Yes	No	No	No

As nouns, gill cleft and gill slit are synonyms defined as:

gill cleft and gill slit: one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes

Other synonyms of gill cleft include branchial cleft.

gill cleft (noun)	gill slit (noun)
one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes	one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes